I did try to reply via the mailing-list, but after three days my
posting is still missing:
qemu -hda openbsd-fw1.img -net nic,macaddr=22:33:77:55:66:00 -net
socket,listen=:11234
qemu -hda openbsd-fw2.img -net nic,macaddr=11:22:33:44:55:66 -net
----------------------------------------------^ (fixed width font)
socket,connect=silence:11234
The first byte of your MAC-address is odd, this indicates that
it is a multicast-address. Strange things will happen if you use
a multicast address where you should use a unicast address.
Please redo your tests with MAC-addresses 52:54:00:11:22:33 and
52:54:00:12:34:56
Greetings,
Mark.